An Arduino was connected to the organ via a UNL2003 darlington array chip. This chip is driving some reed relays which make the organ connections to create the sine wave tones. With that hardware in place it’s a matter of formatting data to generate the target audio. [Forrest] wrote his own Arduino sketch which takes characters from the serial port (pushed over USB by the laptop), maps then to a stored 5×7 character font set, then drives the pins to produce the tones. As you can see in the clip after the break the resulting audio can be turned into quite readable text.

A somewhat simpler approach that’s been in some tech column recently, there’s a keyboard design called “ASETNIOP” – it’s a chord-keyboard design for 10 fingers, only cares about which fingers are down, not where they are, so it can be used with data gloves or an iPad or a piano keyboard. So you could use the piano/organ keyboard to make sounds and the Arduino to decode them into text.